A materials handling facility, such as a fulfillment center, has a multitude of item storage locations for storing an inventory of items. The exact locations of specific items in the inventory of items may be assigned via a computing system. For instance, the computing system may assign item X to be stored in bin Y. However, an agent directed to store item X in bin Y may accidentally store item X in bin Z due to human error. When another agent is later directed by the computing system to pick item X from bin Y, the other agent may be unable to find the item because it is not in the assigned bin. Also, when the computing system later directs another agent to store item Q in bin Z, the agent may discover that space in bin Z is unavailable.